1. Field of the Invention
The invention relates to an improved automatic tissue processor for processing tissue samples for histological analysis.
2. Description of the Related Art
U.S. Pat. No. 6,058,788 describes a tissue processor apparatus featuring a plurality of containers arranged one beside the other and a complex mechanical mechanism for moving tissue samples from one container to the next. Object holders fastened on lifting means are positioned over the containers. The lifting means include a turntable and a rotatably mounted guide rod translated by drive means in a direction perpendicular to the direction of rotation of the turntable. This tissue processor device is complex in character and costly to operate and maintain.
U.S. Pat. No. 4,834,943 describes a tissue processor apparatus for preparing resin-impregnated specimens for microscopic examination. This apparatus comprises a stack of embedding boxes, each containing a specimen, to which specimen preparation reagents are fed by a delivery pump. The specimen preparation reagents fed to the stack are shaken by a reagent shaker mechanism.
U.S. Pat. No. 4,688,517 describes a tissue processor apparatus including a rotatable table, which carries either the samples or solutions in which the samples are to be immersed. The apparatus comprises complex mechanical mechanisms for rotating the table and causing the table to move up and down. This tissue processor device is mechanically cumbersome and costly to manufacture and maintain.
U.S. Pat. No. 3,889,014 describes a tissue processor programmed for fixation, dehydration and clearing of tissue specimens, utilizing a porous receptacle for each specimen and a processing chamber adapted to contain a plurality of the receptacles. The chamber is connected to a plurality of containers, some of which are refrigerated, and which contain various processing solutions. The solutions are individually piped to the chamber through a remotely controlled valve and manifold associated with a metering pump. This arrangement is reported to minimize fluid contamination and allow each solution to be precisely metered, brought to, retained in and drained from the chamber, to enable specimens to be contacted with reagent solutions according to an automatic programmed time sequence. The program may be varied as to number of cycles per solution, as to the number of solutions per program, as to time per cycle and as to starting and terminal solutions in the program. This tissue processor suffers from clogging and associated problems attributable to inconsistent heating of wax containers and deficiencies in the complex apparatus used to transfer heated wax to the processing chamber.
Other examples of tissue processor technology are described in U.S. Pat. Nos. 3,526,203; 3,771,490; 3,227,130; 2,959,151; 2,386,079; 2,341,198; 2,157,875; 2,959,151; 3,400,726; 2,681,298; and 2,684,925.
Against the background of the above-described state of the art, there is a need in the art for an improved tissue processor that is economical to manufacture, operate and maintain, and is highly efficient in operation, employing precision control hardware and software for the execution of tissue processing protocols, without the need for operator intervention during the execution of such protocols.
There is also a need in the art for a tissue processor with an improved heating system for reducing energy consumption and enhancing heating uniformity throughout the system.
There is additionally a need in the art for a tissue processor utilizing a reagent management program for reducing reagent consumption and improving tissue quality.
There is further a need in the art for a tissue processor with an improved fluid transporting system for effective prevention of clogging, reagent carry-over, and other associated problems characteristic of current tissue processor systems.
The present invention in a broad aspect relates to a tissue processor, comprising:
(a) a retort chamber for processing tissue;
(b) a wax storage chamber comprising one or more wax containers;
(c) a reagent storage chamber comprising one or more reagent containers;
(d) a fluid transporting system communicatively connected with the retort chamber, said fluid transporting system comprising a selector for selectively connecting the retort chamber with any one of the wax containers or the reagent containers; and
(e) multiple heating elements for heating the retort chamber, the wax storage chamber, and all or any parts of the fluid transporting system;
(f) a pumping system communicatively connected with the retort chamber for pneumatically driving fluid into or out of the retort chamber via said fluid transporting system; and
(g) a computerized central control system for automatic monitoring and managing components (a)-(f).
In a specific embodiment of the present invention, the wax containers and reagent containers are interchangeable plastic bottles that are configured to be installed in slots in their respective storage chambers. Each container may comprise a quick-connect device for establishing fluid communication from such container to the selector of the fluid transporting system, so that such container can be selectively connected to the retort chamber.
In another embodiment of the present invention, the selector of the fluid transporting system comprises a rotary valve controlled by a Maltese Cross gear. Such Maltese Cross gear only allows the rotary valve to rest at a set of predetermined positions. Each of these predetermined positions aligns the rotary valve to form a fluid communication path that connects a particular wax or reagent container with the retort chamber, so that wax or reagent will be supplied to the retort chamber from the particular container.
The position of the rotary valve can be readily monitored by a position sensor mounted on the body of the rotary valve. Moreover, such position sensor can be operative coupled to the computerized central control system for outputting information about position of the rotary valve. An operator can also input command through the central control system to instruct the selector to rotate the rotary valve to a desired position, thereby supplying fluid from a particular container to the retort chamber.
In a further embodiment of the present invention, the wax storage chamber and the fluid transporting system are positioned in a unitary housing so that they can be co-heated by a common set of heating elements. Alternatively, the fluid transporting system can be indirectly heated by heating elements mounted on the wax storage chamber, which is particularly advantageous for preventing overheating of the fluid transporting system and for reducing overall energy consumption.
In order to prevent wax from clogging, the retort chamber, the wax storage chamber, and/or the fluid transporting system are heated to a temperature sufficient for maintaining wax contained therein in a liquid state, with the temperature being controlled to avoid burning the wax.
In order to achieve effective heating and thermal control of the wax storage chamber, a multiplicity, e.g., five to fifteen, of heating elements are preferably mounted in and around the wax storage chamber. These heating elements can be generally divided into three groups: (a) internal heaters placed between each two wax containers inside the wax storage chamber, preferably in a separator used to separate wax containers from each other; (b) external heaters on each side wall as well as the floor of the wax storage chamber; (c) supplemental heaters on each side wall of the wax storage chamber, provided that such side wall is proximate to the fluid transporting system, for promoting co-heating or indirect heating of the fluid transporting system.
In a further aspect of the present invention, the computerized central control system comprises means for monitoring and controlling pressure and/or temperature within the retort chamber. Such means may include, but is not limited to, thermostats, thermocouples, temperature sensors, thermometers, etc.
In yet another aspect, the computerized central control system has reagent management capability, via execution of a reagent management software program.
The reagent management program enables the central control system to perform various tasks relating to effective reagent management. For example, the central control system can store the number of uses of each reagent in its memory, and whenever a particular type of reagent is needed for processing tissues, the central control system instructs the tissue processor to use the least used reagent within that type, which (as the least used) is the cleanest available. The central control system can also output information regarding available wax and reagents loaded in the tissue processor, so that operator of such tissue processor will be able to timely refill wax and reagents when necessary. Specifically, the central control system in one embodiment is arranged to detect a need for replacement of wax or reagent in a wax or reagent container, according to operational limits that are predetermined or otherwise specified by the operator, and to communicate such need to the operator through an output device. Such output device may include any audio or visual display known in the art.
The reagent management program, in a specific embodiment of the present invention, enables the central control system to accept and store input by an operator, which defines operational limits regarding usage of wax or reagent. Preferably, such operational limits are container-specific. More preferably, such operational limits correlate to the amount of tissue specimens processed by wax or reagent from a specific container, evaluated by: (1) the cumulative weight of specimens processed (with each specimen being assigned a weighting factor, depending on its size); (2) the number of tissue processes conducted and/or the number of tissue cassettes processed.
The central control system of the present invention may accept commands from the operator to zero the number of processes conducted and/or the number of cassettes processed by one or more containers, so that the operator may reinitiate the reagent management program after replacing or renewing reagents in all containers.
Alternatively, the central control system may automatically act, without the operator""s intervention, to zero the above numbers, when the mode of the reagent management program has been changed (e.g., from a single container mode to a group container mode, as described more fully hereinafter), or when the operator activates or deactivates the reagent management program, or when the operator modifies a definition of a reagent group and/or a limit of a reagent group.
When performing reagent management tasks, the central control system may operate in either a single container mode or a group container mode.
In a single container mode, the central control system manages each fluid container as a separate entity, assigning a defined usage limit to each container depending on what type of reagent it contains. When the defined usage limit of a particular container is reached, the central control system outputs an indication that such limit is reached. Optionally, the central control system prompts replacement of such container automatically.
In a group container mode, each container is managed as a member of a container group containing the same or similar type of reagents, and each group is assigned a defined usage limit depending on what type of reagents it contains. The central control system thereafter monitors usage of each reagent in a particular container group and instructs the processor to use reagents according to an order, so that for each tissue process, the least used reagent (i.e. the cleanest) is used first. When the usage limit for a particular container group is reached, the central control system outputs an indication that the limit is reached. Optionally, the central control system prompts replacement of the most used reagent (i.e., the dirtiest).
In another aspect of the present invention, the central control system is capable of executing a reverse processing program to instruct the tissue processor to reverse-process a tissue sample that has already been processed. Such reverse processing program enables to the tissue processor to unprocess unsatisfactory samples and to reduce tissue damage or waste. Preferably, the central control system, when executing such reverse processing program, instructs the tissue processor to execute steps of a tissue processing protocol in reverse order, starting at the last non-zero time of such protocol.
In a further aspect of the present invention, the pumping system of the tissue processor is configured to alternatively depressurize and pressurize the retort chamber to effectuate fluid flow into and out of the retort chamber. Specifically, the pumping system forces wax or reagent to flow into the retort chamber from a wax or reagent container via the fluid transporting system, by draining air out of the retort chamber to lower pressure in the retort chamber to below the ambient. Alternatively, the pumping system pumps air into the retort chamber to raise pressure therein to above the ambient, thereby forcing wax or reagent out of the retort chamber back into the wax or reagent container via the fluid transporting system.
The tissue processor of the present invention may further comprise one or more purge reagent containers capable of being selectively connected to the retort chamber by the selector of the fluid transporting system, for purging the retort chamber to remove wax residue therefrom.
In still another aspect of the present invention, the tissue processor comprises at least one wax purification device, which functions to bubble air through the wax containers and remove volatile contaminants from the wax.
In yet another aspect, the tissue processor comprises a filtering system for removing contaminants from air discharged by the tissue processor so as to reduce undesirable exhaust fumes.
Other aspects, features, and embodiments of the invention will be more fully apparent from the ensuing disclosure and appended claims.